Skip to main content

Full text of "Handbook Of Chemical Engineering - I"

See other formats


172
CHEMICAL ENGINEERING
to the character of the compression curve. The horizontal scale shows pressure ratios and the vertical scale ratio of work or horsepower for two- or three- stage compression, to the work that would be required for single-stage compression as determined from Fig. 31. For example, for a pressure ratio of 8, or a discharge of 117.6 Ib. per square inch absolute on a suction pressure of 14.7 Ib., the work for a compression following the
equation pi^i1'4 = p*vj'* would be 85.2 per cent of the work for the same conditions single-stage if two-stage were used, and 81 per cent of it if three-stage compression were used.
Effect of Altitude.—As the density of the atmosphere decreases with the altitude, a compressor located at a high altitude will take in a smaller weight of air at each stroke. The reduction of pressure at the inlet affects the power expended in compressing the air, but the decrease in power required does not vary in the same ratio as the decrease in
capacity. For this reason compressors to . ^ 1,1-1 i,-, j i u i        .1
be used at high altitudes should have the
steam and air cylinders properly proportioned to meet the varying conditions at different levels.   Table 12, published by the Sullivan Machinery Co., of Chicago,
TABLE 12.—VOLUMETRIC AND HORSEPOWER COEFFICIENTS FOR TWO-STAGE AIR
COMPRESSION
n~I.S
10   11    \l   13   14   15 Ratio of Pressures.
FIG. 32.—Chart for determining the work done in two- and three-stage air compression (Lucke).
		Terminal  gage pressure,  pounds per square inch													
	Barometer	70		80		90		100		120		140		150    ,	
Altitude, feet	pound per square inch	'sepower (fficients	umetric fficients |	'sepower fficients	umetric fficients	rsepower fficients	umetric fficients	rsepower fficients	umetric fficients	rsepower j fficients j	umetric fficients	rsepower fficients	lumetric fficients	rsepower | fficients j	lumetric ; fficients 1
		0 o w«	s° P>  0	II	II	0 £ ws	£i	°8 M o	1% >> o	M  0 H o	°g K*   0	£° pq <y	£1	£§	£8 t> 0
Sea level	14.72	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00	1.00
1,000	14.17	0.98	0.97	0.98	0.97	0.98	0.97	0.98	0.97	0.98	0.97	0.98	0.97	0.98	0.97
2,000	13.64	0.97	0.94	0.96	0.94	0.96	0.94	0.96	0.94	0.96	0.93	0.96	0.93	0.96	0.93
3,000	13.13	0.95	0.91	0.95	0.91	0.94	0.91	0.94	0.91	0.94	0.90	0.94	0.90	0.94	0.90
4,000	12.64	0.93	0.88	0.93	0.88	0.93	0.88	0.92	0.88	0.92	0.87	0.92	0.87	0.92	0.87
5,000	12.17	0.91	0.85	0.91	0.85	0.91	0.85	0.91	0.84	0.90	0.84	0.90	0.84	0.90	0.84
6,000	11.71	0.90	0.82	0.89	0.82	0.89	0.82	0.89	0.82	0.88	0.82	0.88	0.81	0.88	0.81
7,000	11.27	0.88	0.80	0.88	0.79	0.87	0.79	0.87	0.79	0.86	0.79	0.86	0.78	0.86	0.78
8,000	10.85	0.86	0.77	0.86	0.77	0.85	0.77	0.85	0.76	0.85	0.76	0.84	0.76	0.84	0.76
9,000	10.45	0.85	0.75	0.84	0.74	0.84	0.74	0.83	0.74	0.83	0.73	0.82	0.73	0.82	0.73
10,000	10.06	0.83	0.72	0.83	0.72	0.82	0.72	0.82	0.71	0.81	0.71	0.81	0.71	0.80	0.70
11,000	9.69	0.82	0.70	0.81	0.70	0.80	0.69	0.80	0.69	0.79	0.68	0.79	0.68	0.79	0.68
12 , 000	9.33	0.80	0.68	0.79	0.67	0.79	0.67	0.78	0.67	0.78	0.66	0.77	0.66	0.77	0.66
13 , 000	8.98	0.78	0.65	0.78	0.65	0.77	0.65	0.77	0.64	0.76	0.64	0.75	0.63	0.75	0.63
14,000	8.64	0.77	0.63	0.76	0.63	0.76	0.62	0.75	0.62	0.74	0.62	0.74	0.61	0.74	0.61
15,000	8.32	0.75	0.61	0.74	0.61	0.74	0.60	0.74	0.60	0.73	0.59	0.72	0.59	0.72	0.59